The invention relates to a fireproof coating which forms an insulating layer and is based on carbon-forming substances forming a foam layer in the case of a fire, film-forming binders, blowing agents and conventional assistants and additives.
Fireproof coatings forming an insulating layer, also referred to as intumescent coatings, are distinguished by the fact that they foam on appropriate action of heat in the case of a fire and, as a result of this foaming of the abovementioned fireproof coating, the passage of heat to steel structures, ceilings, walls, cables, pipes and the like is prevented or at least impeded.
U.S. Pat. No. 4,965,296 A1 describes a flame-retardant material which is composed of a flame-retardant coating material and an electrically conductive material. The flame-retardant coating material comprises foam-forming and carbon-forming substances, a gas-producing compound, a film-forming binder and corresponding solvents. Optionally, conventional, further ingredients may be present.
U.S. Pat. No. 4,879,320 describes a similar flame-retardant composition, to which however ceramic fiber material is added instead of a conductive material.
U.S. Pat. No. 5,225,464 describes an aqueous intumescent formulation based on a react on product of phosphoric acid, melamine and monoammonium phosphate, which formulation, with pentaerythritol, chlorinated hydrocarbons and further compounds, in particular, polyvinyl acetate, is said to give an improved intumescent coating material.
Numerous intumescent formulations are disclosed in "Fire Retardants Formulations Handbook" (Author: Vijay Mohan Bhatnagar, 1972).
DE 42 18 184 A1 describes an aqueous binder mixture comprising an aqueous solution and/or dispersion of a combination of a) at least one NCO prepolymer which is soluble and/or dispersible in water in the presence of component b) and has urethane groups and blocked isocyanate groups and b) a polyamine component comprising at least one (cyclo)aliphatic polyamine having at least two primary and/or secondary amino groups.
Finally, DE 43 43 668 describes expandable, flame-retardant coating materials comprising at least
from 4 to 25% by weight of a film-forming binder, PA1 from 10 to 4% by weight of ammonium polyphosphate, PA1 from 8 to 40% by weight of at least one substance which carbonizes under the action of heat, PA1 from 6 to 25% by weight of a blowing agent, PA1 from 0 to 5% by weight of a dispersant, PA1 from 0 to 25% by weight of fillers. PA1 from 5 to 30 parts by weight of a film-forming binder, PA1 from 15 to 50 parts by weight of a substance forming a foam layer, PA1 from 5 to 25 parts by weight of a carbon-forming substance, PA1 from 5 to 50 parts by weight of the melamine salt and/or of the guanidine salt and PA1 from 10 to 50 parts by weight of conventional assistants and additives. PA1 from 10 to 20 parts by weight of a film-forming binder, PA1 from 25 to 40 parts by weight of a substance forming a foam layer, PA1 from 7 to 15 parts by weight of a carbon-forming substance, PA1 from 7 to 40 parts by weight of the melamine salt and/or of the guanidine salt and PA1 from 20 to 40 parts by weight of conventional assistants and additives. PA1 homopolymers based on vinyl acetate, PA1 copolymers based on vinyl acetate, ethylene and vinyl chloride, PA1 copolymers based on vinyl acetate and the vinyl ester of a long-chain, branched carboxylic acid, PA1 copolymers based on vinyl acetate and di-n-butyl maleate, PA1 copolymers based on vinyl acetate and acrylic esters, PA1 copolymers based on styrene and acrylic esters and/or copolymers based on acrylic esters, PA1 vinyltoluene/acrylate copolymers, PA1 styrene/acrylate polymers.
The disadvantage of the abovementioned fireproof coating is in general that they are halogen-containing or do not have a sufficiently wide range of uses.
Particularly in the case of formulations which contain melamine as blowing agent, it was found that these combinations release relatively large amounts of ammonia (NH.sub.3) at elevated temperature and high atmospheric humidity, for example under tropical conditions.